Pelleted seed product



Patented Sept. 15, 1953 PELLETED SEED PRODUCT Ross M. Hedrick and DavidT. :Mowry, Dayton,

Ohio, assignors to Monsanto Chemical Company, St. Louis, Mo., acorporation of Delaware No Drawing. Application June 26,1952, Serial No.295,846

The portion of the term of the patent subsequent to January 13, 1970,has'been disclaimed and dedicated to the public Claims.

This invention relates to new and improved processed seeds, and morespecifically toseeds coated for the facilitation of planting operations,for increase in germination of the seeds,and for enhanced growthcharacteristics of the plant.

Seed coating is well-known in th agricultural arts, and the adaptabilityof the coatedseeds to mechanical planting machines and the incidenteconomies of time and labor are well-known. Seeds are customarily coatedwith clays having natural adhesive properties, for example,montmorillonite and other bentonitic expanding lattice clays, but suchcoatings are known to retard the rate of germination and to reduce theproper-- tionof ultimate seed germination. It is also wellknown that theclays or other coating compositions may be structurally reinforced byusing various resinous adhesives or-binders. Although Water-solubleadhesives have been used heretofore, for example alginic acid, these arenot longlived in the soil, but are subject to decomposition by soilbacteria. Thus many of the seed coating benefits may be lost prior tothe germination 'of the seed or the emergence of the seedling.

In copending applications, Serial Nos. 148,521 and 148,522, filed March8, 1950, by Ross M. Hedrick and David T. Mowry, now abandoned, theretion of the fine soil particles and the agglomeration of the fineparticles into crumbs or aggregates which have greatly improvedwater-stability. The treated soilsso prepared are of much more enduringaggregated state and provide increased aeration, increased moistureretention,

and enhanced nutrient utilization and other benefits usually experiencedin fertile soils. The benefits described in the copending applicationsare especially noticeable in clay soils of poor structure and loworganic content, although the more permanent water-stability will resultfrom the treatment of even the most fertile soil in which the normalaggregation is short-lived.

In copending application, Serial No. 271,280, filed February 12, 1952,by Ross M. Hedrick and David T. Mowry, now issued as United StatesPatent No. 2,625,529, there is described alarge class of syntheticpolyelectrolytes which manifest similar improvements when used intreating surface soils. All of these are water-soluble polyelectrolyteshaving a substantially continuous carbon chain derived by thepolymerization of an aliphatic unsaturated carbon to carbon linl age andwhich are all substantially high molecular weight, for example weightaverage molecular weights in excess of'10,000. The continuous carbonchain of these useful-polymers is that derived by usual olefinicpolymerization of double bonded carbon atoms which may be branchedbutshould not contain a large number of cross-linking structures. Bywater-soluble as usedin the definition of the classof useful polymers,compounds soluble in distilledwater or in the soil water are included,as also are the polymers which swell in thepresence of water and-in theswollen form are dispersed in-the aqueous media.

The present application 'is a continuation-inpart of said applications,Serial Nos. 148,521and 148,522 and 271,280.

It has been found that the water-soluble :synthetic polyelectrolytesdescribed in the saidapplications of which this. isacontinuation-impart, may be used as the resinous; binders forcoatingcompositions inthe manner known tothe: art, but that certain inherentbenefits are :derived which are not common with respect. tocompositionsused heretofore. By using one of the polyelectrolytes in theseed'coating composition, it is possible to modify the structure-of thesoil ;in the vicinity of the. planted seed, and the seedgermination,seedling emergence, root growth and gen eral welfare of the resultingplant :will benSllbstantially improved.

Althougha wide variety of the synthetic :polyelectrolytes are describedin. the said copending application, Serial No. 271,280, of greatest.importance are those which provide optimum effect on th soil, and whichare prepared from relatively available and inexpensive raw materials. Ofparticular importance in the'useas seed coating materials are thevarious acid-alkali metal or lime hydrolyzed polyacrylonitriles andother polymeric acrylic acids and salts thereof,"polymethacrylic acidand various salts of the polymeric methacrylic acids, which may beprepared-by polymerization of methacrylic'acid or by theihy drolysis ofvpolymethacrylonitrile, the: sulfonated polystyrenes and salts thereof,copolymers of maleic acid and other copolymerizable. mono-- mers, andthe various salts thereof, especially the sodium, potassium, ammoniumand calcium salts of the copolymer of maleic acid and vinyl acetate, thealkali metal and ammonium salts of the copolymer of maleic acid andisobutylene, the half amide-half ammonium salt of the copolymerof maleicacid and-isobutylenathe partial calcium salt of the copolymer of vinylacetate and the partial methyl ester of maleic acid and homolo gouscopolymers. and salts.

The'new'pelleted' seed products are prepared by methods directlyanalogous to those of the prior art. The seed is placed in a drumrevolving on a horizontal axis, thereafter being slightly moistened byan aqueous mist or vapor. The finely divided polymer, or a mixture ofpolymer and other compound, is blown into the drum and deposited on themoist surface by the rotary action of the drum. The coating on the seedsincreases with time, and by proper control a coat of any desiredthickness and weight can be obtained. The tendency of the seed to coherecan be prevented by regulation of the rotary action of the drum. Theperiod of time and the thickness of the coat will depend upon the sizeand the shape of the original seed and the purpose for which the coatingis applied. In processing small seeds it is generally desirable to use acoating of substantial thickness so that the coated seed product will beapproximately the diameter of larger seeds usually planted by standardautomatic machinery. With larger seeds and those of substantiallyspherical shape the coating will be thinner and may depend more upon thequantity of polymer or other coating composition ingredient desired.

Through the use of polymeric water-soluble polyelectrolytes of the typedescribed herein all of the required adhesive and bonding actions areachieved, but in addition the polymer is available at the site of theplanted seed to benefit theseed germination and growth of the plant. Ifthe proportion of the polymer is substantial, the soil water in which itwill ultimately dissolve, will transmit the polymer from the pelletedseed product to the adjacent soil whereby the soil aggregates will bestabilized and rendered resistant to the usual slaking and erosionactions. The soil so treated will contain interstices providing airaccess and beneficial drainage characteristic to the soil. In thismanner a single planting operation will provide structural improvementin the soil at the site of the seed where these benefits are mosturgently required. The better aeration will also provide optimumconditions for maximum germination, and after germination will provide aporous root bed and a soil of improved water retention and fertility,even in heavy clay soils of normally poor physical structure.

The composition of the coating composition will depend upon the intendeduse of the pelleted seed product. When resinous binders or adhesives arenot used, it is necessary that the base composition be a substance withnatural adhesive properties. However, when the polyelectrolytes areused, a wide variety of base compositions may be used, for example clay,sand, diatomaceous earth, fiyash, chalk and crushed limestone. Theproportions of polymer and filler will vary widely depending upon thephysical properties of both. Some of the polymeric polyelectrolytes arevery hygroscopic and have greater powers of adherence than others.Similarly the various fillers differ in physical properties and some mayrequire more adhesive than others. The particular combination ofpolyelectrolyte and filler can readily be determined by one skilled inthe art, but in general a composition of from one to 50 per cent polymerwill be satisfactory for most applications.

The pelleted seed compositions may include other compounds to provideadditional beneficial results. For example, if the seed pellets are tobe used in soil deficient in plant nutrients, then it is often desirableto include in the pellet a suitable fertilizer compound. Thus, theprincipal nutrient elements, nitrogen, phosphorus and potassium ormixtures thereof may be included.

.. Similarly the essential trace elements such as boron, manganese,molybdenum, cobalt and iron may be included. In general the fertilizingcomponents in which the soil is deficient should be supplied. Similarlyorganic fertilizers may be compounded with the polymer and used as thecoating compositions. Since the polyelectrolytes may react with saidnutrient compounds or otherwise be adsorbed, they often provide a sourceof nutrient value over a longer period of time.

Since many types of seeds, and particularly in certain areas, aresubject to fungus attack, it is often desirable to include a fungicide.The particular fungicide used will depend upon the suspected fungus,which is most frequently encountered with the particular seed beingprocessed. Thus, bordeaux mixture and other copper containing compounds,mercury, salts, formaldehyde and sulfur may be used effectively. Theselection of an effective fungicide will be understood by one skilled inthe art.

The pelleted seed compositions may also include an insecticide. Sincemany seedlings are subject to attack by cutworms and other insect larvaein the ground, a suitable effective insecticide or insect repellent maybe used, for example dichlorodiphenyltrichloroethane, arsenicderivatives, organic sulfur compounds and nicotine or other alkaloidderivative.

The use of other compositions, for example indolacetic acid or othergrowth promoting hormones, germination stimulants, and other additivesmay be required in particular circumstances. The selection and additionof functional additives is well-understood by one skilled in the art.Obviously compounds which in addition to beneficial effects havedeleterious effects on the seeds should be avoided.

What we claim is:

l. A pelleted seed product comprising a seed having adhered thereto acomposition including a polymeric water-soluble polyelectrolyte having aweight average molecular weight of at least 10,000, and having astructure derived by the polymerization of a monoolefinic compoundthrough the aliphatic unsaturated group.

2. A pelleted seed product comprising a seed having adhered thereto asynthetic water-soluble polyelectrolyte having a structure derived bythe polymerization of a monoolefinic compound through aliphatic carbonto carbon unsaturation and having a molecular weight such as to improvethe water-stability of soil aggregates.

3. A pelleted seed product comprising a seed having a coating of acomposition including a polymeric water-soluble polyelectrolyte having aweight average molecular weight of at least 15,000, and containing asubstantially linear structure derived by the polymerization of analiphatic unsaturated group.

4. A pelleted seed product comprising a seed having a coating of acomposition including a synthetic polyelectrolyte containing asubstantially linear structure derived by the polymerization of acompound through aliphatic carbon to carbon unsaturation and having amolecular weight such as to improve the water-stability of soilaggregates.

5. A pelleted seed product comprising a seed having adhered thereto acomposition including a polymeric water-soluble polyelectrolyte having aweight average molecular weight of at least 10,000, said polymer beingselected from the class consisting of: polymers of acrylic acid, saltsof polymers of acrylic acid, salts of hydrolyzed polymers ofacrylonitrile, hydrolyzed polymers of acrylonitrile, polymers ofmethacrylic acid, salts of polymers of methacrylic acid, salts ofhydrolyzed polymers of methacrylonitrile, hydrolyzed polymers ofmethacrylonitrile, salts of copolymers of unsaturated polycarboxylicacids and at least one other monoolefinic monomer, copolymers ofunsaturated polycarboxylic acids and at least one other monoolefinicmonomer, salts of hydrolyzed copolymers of unsaturated polycarboxylicacid anhydrides and at least one other monoolefinic monomer, hydrolyzedcopolymers of unsaturated polycar'boxylic acid anhydrides and at leastone other monoolefinic monomer, salts of copolymers of the partial alkylesters of unsaturated polycarboxylic acids and at least one othermonoolefinic monomer, copolymers of the partial alkyl esters ofunsaturated polycarboxylic acids and at least one other monoolefinicmonomer, salts of sulfonated polymers of hydrocarbons containingaliphatic unsaturation, sulfonated polymers of hydrocarbons containingaliphatic unsaturation, polymers of amines containing aliphaticunsaturation, and polymers of amides containing aliphatic unsaturation.

6. The product defined by claim 1 wherein the polyelectrolyte is acalcium salt of a hydrolyzed polymer of acrylonitrile.

7. The product defined by claim 1 wherein the polyelectrolyte is asodium salt of a hydrolyzed polymer of acrylonitrile.

8. The product defined by claim 1 wherein the polyelectrolyte is acopolymer of vinyla-cetate and the reaction product formed by partiallyesterifying maleic anhydride with methyl alcohol.

9. The product defined by claim 1 wherein the polyelectrolyte is anammonium salt of the copolymer of isobutylene and maleic acid.

10. The product defined by claim 1 wherein the polyelectrolyte is acalcium salt of the copolymer of vinyl acetate and maleic anhydride.

11. The product defined by claim 2 wherein the polyelectrolyte is acalcium salt of a hydrolyzed polymer of acrylonitrile.

12. The product defined by claim 2 wherein the polyelectrolyte is asodium salt of a hydrolyzed polymer of acrylonitrile.

13. The product defined by claim 2 wherein the polyelectrolyte is acopolymer of vinylacetate and the reaction product formed by partiallyesterifying maleic anhydride with methyl alcohol.

14. The product defined by claim 2 wherein the polyelectrolyte is anammonium salt of the copolymer of isobutylene and maleic acid.

15. The product defined by claim 2 wherein the polyelectrolyte is acalcium salt of the copolymer of vinyl acetate and maleic anhydride.

ROSS M. HEDRICK. DAVID T. MOWRY.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 79,765 Lafferty July 7, 1868 1,319,157 Lingle Oct. 21, 19192,553,577 Hale May 22, 1951 2,579,734 Burgesser Dec. 25, 1951 2,579,735Burgesser Dec. 25, 1951 2,582,194 Dudley Jan. 8, 1952 2,625,529 HedrickJan. 13, 1953 2,625,471 Mowry Jan. 13, 1953

1. A PELLETED SEED PRODUCT COMPRISING A SEED HAVING ADHERED THERETO ACOMPOSITION INCLUDING A POLYMERIC WATER-SOLUBLE POLYELECTROLYTE HAVING AWEIGHT AVERAGE MOLECULAR WEIGHT OF AT LEAST 10,000, AND HAVING ASTRUCTURE DERIVED BY THE POLYMERIZATION OF A MONOOLEFINIC COMPOUNDTHROUGH THE ALIPHATIC UNSATURATED GROUP.